This invention relates to planar optical devices and, more particularly, to arrangements for pumping integrated arrays of such devices.
A variety of optical devices made in the form of planar optical waveguides are known. Multiple such devices can be fabricated in an integrated fashion on a substrate to provide a microminiature component that is useful in optical signal processing networks.
An advantageous planar device that functions as an optical amplifier is described in U.S. Pat. No. 5,119,460. The device described therein amplifies optical signals by stimulated emission from erbium ions. Erbium ions are excited to a lasing level by coupling pumping radiation into an active erbium-doped region of the device.
In accordance with the teachings of the aforecited patent, signal and pumping radiation are combined and then injected into the active region of each device (see, for example, FIG. 2 of the patent). For large integrated arrays made on a single substrate, such device-by-device pumping can obviously lead to complicated topologies and difficult routing problems.
Accordingly, efforts have continued by workers skilled in the art directed at trying to improve the structural arrangement of planar optical amplifiers in an integrated array. In particular, these efforts have been directed at trying to devise a more effective way of pumping the amplifiers. It was recognized that these efforts, if successful, could lead to more compact and lower-cost integrated arrays for use in optical signal processing networks.